Studies in Serotonin
by kate221b
Summary: 'What Mycroft hadn't understood, what none of them understood, was that he wasn't an addict. He was a user and there was a world of difference between the two.' An exploration of Sherlock's drug use in HLV and beyond.


This is set immediately after Sherlock's disappearance from the hospital in HLV and immediately before the scene in Leinster Gardens, and is an exploration of Sherlock's drug use, and the possible reasoning behind it. But then he's not an addict, he's just a user - isn't he?

* * *

Allowing yourself to become lost was easy, Sherlock knew that. It was finding your way back that was hard.

But this time - this time was different. This was about John. About keeping him safe. And because of that, Sherlock knew that he couldn't allow himself to disappear this time however much he wanted to. He had to stay focused and ensure that he could find his way back. To John. And to Mary and the devastation that she had wrought on John's life. He had to find a way to solve this.

Which brought him to the next issue that he faced. This wasn't about facts. He had those. And he had a plan already being orchestrated by Billy. All Sherlock needed to do was to was to get to Leinster Gardens and complete the finishing touches. That gave him just under two hours to deal with the more tricky aspect. Emotion.

Slipping through the gap between two office buildings, he paused for a moment, checking there were no witnesses before swiftly opening a battered door, half hidden by shadow on his left, and closing it behind him. A set of stairs led down to a warren of damp, concrete corridors which twisted and turned deep under the street. In a matter of minutes he had reached his destination, and let himself in with a practised flick of the padlock, checking that the tells for uninvited guests had not been disturbed as he went.

The lab looked exactly as he had left it, but the exertion of getting there left him oddly light-headed. Side-stepping the stool standing at the workbench, he instead stood for a moment with his back to the bare concrete wall, before allowing himself to slide down it to sit on the floor, legs straight out in front of him like a child. He rested his head back, eyes closed and waited for the faintness to pass, wondering if he was going to pass out and what would happen if he did. He had left no list for Mycroft to find this time.

The ketamine that Billy had procured for him was wearing off and the discomfort from his injuries slowly returning. With each breath he could feel the pull of the stitches deep inside his chest cavity, and then with the abruptness that only ketamine could provide, he was suddenly viewing his own body from the inside, watching the beating of his heart, still bruised from the gunshot wound, a surprisingly compact organ the size of a man's fist, too small and fragile-looking for the demands that humanity required of it. He could see the line of sutures in the fibrous pericardial sac that surrounded this delicate organ and to its right, a trickle of the blood from the hilum of his lung where the bullet had grazed it on its way through, running down and pooling in a glistening lake below him. He could hear the valves closing and the swoosh as the ventricles filled with blood prior to contraction, feel the vibration as their force pushed blood through the vessels he was resting his hand on. He could hear it all, see it all, and it threatened to suck him down into a soothing lullaby of flow and pulsation.

Sherlock squeezed his eyes tightly shut and with an effort forced himself to focus on the physical world around him; the coldness of the stone floor beneath his hands, placed flat on the floor, the hardness of the wall behind his head, the familiar smell of chemicals and damp inside the lab that was one of his best kept secrets. This was an emergent phenomenon from the ketamine, nothing more. He knew that. He couldn't really see into his chest, he had no evidence other than the thudding of his racing heart beat that his exertions that day had re-opened his old injuries. He forced himself to slow his breathing - deep breath in, hold it for the count of two, breath out for five and repeat. He had almost forgotten how unpleasant the come-down from ketamine could be without the aid of benzodiazepines to slow the transition back to reality. He had refused the diazepam that Billy had offered, unwilling to risk anything that might slow him down during his escape. He needed all of his prefrontal cortex as fully functional as possible for what he needed to do next, not further hampered by the burst of inhibitory GABAergic activity that the diazepam would provide. Besides, he mistrusted Billy's supply. Just because it looked like a diazepam tablet and came in a blister pack didn't mean that it hadn't been cooked up in some backstreet lab and expertly packaged to look like the genuine article.

His breathing was becoming easier now, the thudding of his heart less disturbing and when he opened his eyes, the room swam back into focus. Cautiously he pushed himself to his feet, waited a few seconds for the dizziness to subside and then walked over to the work bench. He reached into the bottom drawer, pulling out the old tripod and Bunsen burner left there to distract any intruders that should happen to come looking, removed the false bottom from the drawer, and took out the treasure hidden beneath.

Inside the cavity left by the false shelf was a dark brown leather box, slightly smaller but deeper than the copy of Gray's anatomy he kept on his bookshelf in 221b. He clicked open the antique catches and felt a thrill of anticipation, as always, at the contents revealed within. The lid of the box contained two rows of beautifully crafted glass and silver vials, the proud property long ago of a Victorian pharmacist or maybe even a physician, like John. In each vial was a white powder, but the colours of the substances held within were a subtle range from almost transparent through to a pale cream. In the base if the box, in half a dozen small jars, were a rainbow of other pills and tablets, but it was to the lid that Sherlock turned his attention now. Here laid out before him were all of the answers that he needed, the solution to any problem he might face. He just had to decide which ones would take him there.

His fingers danced along the top row, before settling on the third vial along. Without bothering to check the label, he picked it up and tilted it to the light, shook it slightly and watched the powder scintillate as the beams of light refracted off them. Lysergic acid diethylamide, or to give it its abbreviated name, LSD. An isomer of his own creation, carefully engineered through years of experimentation, of meticulous documentation of technique and effect. It had been crafted to reduce the onset time from the frustrating thirty minute threshold thought to be unavoidable irrespective of the method of administration to a mere five minutes by substitution of one tiny part of the chiral compound. It was the first drug that he had manufactured himself. The basic form was surprisingly simple - a simple reaction between diethylamine and ergotamine, relatively easily produced even in his small laboratory by growing ergot fungus on agar plates and combining it with diethylamine which was more readily procurable. The engineered form had taken him years. The black diaries lining the back of the workbench carefully documented all of his experiments with it; time and method of administration; dose; time of onset of action; duration; effect produced, with side notes documenting the neurotransmitter pathways that he believed he had been activated.

LSD was well known to act on glutamate pathways in the brain but Sherlock was more interested in its effect on the serotonin receptors, in particular on isolating the action on the specific serotonin receptors, thought to be be responsible for the laying down and retrieval of memories. Developing a compound that enabled activation of this receptor, without activating the other serotonin receptors which reduced access to memory had proved difficult, if not impossible, but this formulation was still far superior to anything that he had ever been able to purchase on the street. Pharmaceutical studies wrote with frustration of the inevitable link between the memory effects of LSD and its hallucinogenic effect, both apparently activated via the same serotonin receptor, but Sherlock had learnt to use this to his advantage in the mind palace. In combination with other agents - a little ketamine to help him enter a dissociative state, some methylphenidate to keep his mind focused and prevent him from drifting inadvertently into the strange corners of his mind palace. And always, always, some diamorphine - heroin, because it worked better that way.

Some of his earlier experiments had left him trapped in nightmare hallucinations for hours, unable to escape the confines of the hellish labyrinth that his own memory palace had become. Careful experimentation with benzodiazepines to switch on the inhibitory pathways that slow down brain activity had proved an effective solution. Taken orally before injecting the other constituents of the cocktail, diazepam had proved to have a delay in onset time that provided the perfect solution - a pharmacological exit door of sorts, a psychological fire escape.

There had been other complications too, issues that had had to be overcome. Some of his earlier experiments into threshold dose, before he had made the tweaks to the compound, had left him with flashback hallucinations for days. Other users had reported the entheogenic effects of LSD and had claimed to have seen the face of God. This had never happened to Sherlock, although he had once seen a ridiculously stereotypical angel, complete with white feathered wings gliding the entire length of Fleet Street, several feet above the ground. And that, he suspected, was as close to heaven as he was even going to get, even with pharmacological help. He had tried to tell John that once, a very long time ago. 'Heroes don't exist, and if they did, I wouldn't be one of them.' A rare moment of poetry, inspired by the tail end of an experiment into an overly-emotive form of the compound, subsequently discarded.

John had been unable to turn him into a hero, but he had in some way at least, aligned Sherlock's moral compass to his. The pull of it had been unescapable. The image of the angel and all that it represented burnt forever in his brain. And when a choice had had to be made, he had made the right one, the heroic one, but without aligning himself to their ranks. 'I may be on the side of the angels, but don't think for one minute that I am one of them.' Angels and demons had haunted his dreams since then, and in the worst of them, his face and Moriarty's switched interchangeably between the angelic and demonic figures which circled each other in a never ending dance. A morality tale worthy of the darkest of Fairytales.

For all of the trials of its invention, the resulting compound was a thing of beauty - chemically as well as physically. He shook the vial again. The triboluminescence that was an odd feature of the salts of the traditional compound had not been lost by the manipulation of the isomer. He watched the crystals shimmer in the light, transfixed for a moment, then reluctantly replaced the vial into the box. Another day, another time, he would allow it to take him deep into his mind palace, but not today. Today he had need of a different kind of chemical.

The box in front of him dated back to early Victorian times, its dark brown leather marked in places by sweat from the fingers of the dozens of previous owners. Sherlock could have found a more modern storage solution, of course he could, but the history in the box had appealed to him. 'Sentiment,' Mycroft would have said, had he known about it, 'Nostalgia. Logic has no room for nostalgia, Sherlock, It clouds the mind, affects the judgment.' And yet Sherlock enjoyed objects - his skull, his Persian slipper, his violin. Objects held memories in themselves, served as a reminder, and some - his violin for example, expanded his memory on its own. He had read with interest the research studies showing that musicians showed expansion of parts of their prefrontal cortexes, simply by the act of practicing and playing different pieces. And so music had proved to be more than an indulgence. In some ways, that too was part of the work.

When Sherlock had found the box, with its two perfect rows of glass and silver vials, the jars in the base and the lidded compartment to the side of them, designed he suspected to hold a silver syringe and other injection paraphernalia, designed in the days when injecting both cocaine and morphine was entirely socially acceptable, then he had known that he had to have it. Not simply for practical reasons, but because sometimes objects were made to be used, and a box with memories of its own appealed to him more than he cared to admit.

He hadn't even quibbled over the price, which had been more than he could easily explain away in the days when Mycroft had control of his finances. Even back then he knew of ways and means of obtaining money that his brother was entirely unaware of. He had paid for the box in cash and given a false name and address for the ledger. Should Mycroft get word of his purchase from one of his many sources then he would no doubt have realised its implications, but to Sherlock's knowledge he remained unaware. Now the glass vials were nearly all filled once more, their contents nearly all either manufactured or purified in this lab and kept safe there, in one of the many forgotten corners of London. Sherlock had stumbled on this place years ago, looking for somewhere warm and dry to sleep during his time on the streets. Located deep within the system of maintenance tunnels, it had once been part of a boiler room, long ago left defunct by other, more modern, heating systems. The door to this secret space appeared from the outside to be rusted and jammed, multiple padlocks making the entrance appear impassable to anybody other than Sherlock. The city was full of secret spaces like this, and while even Sherlock couldn't claim to know them all, the homeless population of London, the underclass that went about unnoticed, almost invisible to the majority of residents, knew about huge numbers of them.

During his time on the streets in his twenties, those times when he had felt the need to disappear for days, weeks, months at a time, Sherlock had picked out a few of these spaces as his own. To start with they had been hiding places, physical spaces in which he could hide his street clothes, and the other equipment that enabled him to slip easily between his privileged life in North London and his other life, his life on the streets, the place where he could lose himself and be truly free.

In the beginning this place had also been used as a place to stash his supply of drugs, back when he used to buy them on the street. But suppliers, even the best suppliers, couldn't guarantee the purity of the substances they procured for you. During his Cambridge days, Sherlock had risked slipping a sample into the gas chromatography - mass spectromatography machine during one of his many all-night sessions in the laboratory working on his dissertation and had been genuinely horrified by the results. His own analysis proved that even the 'best gear' sold to him was rarely more than 65% pure. Baking powder, sugar, nutmeg and even brick dust used to cut the powder were one thing, but fentanyl, quinine and strychnine were something else. Sherlock might be a user, but he liked to know what he was putting into his body. One batch that later turned out to have been cut with high doses of benzodiazepines without his knowledge, left him out cold for several hours and only the kindness of strangers had let him to live to tell the tale. Purifying the substances in the laboratory seemed like a viable option for a short while, until one of his dissertation supervisors 'popped in' on his way back from the pub late one evening and very nearly caught him at it. The knuckle- rapping that he got for knocking a bottle of surgical spirit onto a conveniently placed Bunsen burner and nearly burning down the lab was nothing compared to the implications if she had realised the experiment he was actually conducting. In the chaos he had managed to slip the bag of white powder back into his pocket and the fire had destroyed the rest of the evidence.

For a while after that, he had reverted to simpler and more easily available chemicals - tramadol, temazepam, metamphetamine. Easier to obtain from verified sources, if you had the money then there were always people who were prepared to go and get these prescribed in order to sell them on, or the odd dodgy pharmacist prepared to lose the odd packet from a delivery and claim water damage or mis-counted goods from the suppliers. Back in those days, before colour printers were widely available, you knew what you were getting in the tablets came blister packed in a pharmaceuticals company's box, but the effect was insufficient for his needs and he had found himself contacting his old supplier again within a few months of the fire at the lab.

A secret handshake exchanging a bundle of notes for a bundle of small plastic bags was all that it had taken. It was easy, too easy, and he was too eager to try out his new stash. He had underestimated how much his tolerance had dropped during his months of near-abstinence, and had woken several hours later to the bright lights of an A&E resuscitation room, and Mycroft's disapproving face. Fortunately his parents had been out of the country at the time and had remained blissfully unaware, at least until the summons from the Dean of the college and his rapid rustication for possession of Class A substances on college premises.

He had been lucky to escape a prosecution for possession or given the quantity and variety of the substances found in his room, possibly even for supplying. He suspected that Mycroft had a hand in the mitigation of this to an official warning. Even at twenty-six, Mycroft was already a rising star at GCHQ, was on several government advisory panels, and was becoming a regular visitor to the House of Commons bar. A quiet word in the ear of the then Minister of Justice and a telephone call to the local chef inspector had been all that it had taken. Sherlock had had to promise to attend the local substance abuse service for counselling, and to provide regular samples of drug-free urine. But attending counselling hadn't specified the need to talk, or rather not to talk about himself, and when the third counsellor in a row had exited the session in tears, the director of the service had readily agreed that counselling was no longer required. And as for the clean urine samples - the agreement never specified that the sample had to come directly from Sherlock as it were, only that he had to provide them. Clean urine samples were readily available by the lemonade bottle full on the street, if you knew who to ask and had the appropriate amount of cash in your back pocket.

What Mycroft hadn't understood, what none of them understood, was that he wasn't an addict. He was a user and there was a world of difference between the two. The drugs enabled him to work, they freed up parts of his mind that would otherwise be inaccessible. Over the years he had developed his own personal cocktail cabinet of drugs; precise balances of stimulants and sedatives, amphetamines and hallucinogens, which acted in the correct order and the precise way in which enabled him to enter a dream-like state, work through his mind palace and piece through the evidence to find the answers. A slightly different balance enabled him to delve to the deeper layers, an almost parallel existence, often in a different chronological time, to work through issues from a different perspective. Another mix again enabled him to enter into his own memories in a precise, organised manner, sifting through information until he found tiny details that would otherwise have been irretrievably lost. In short, there was a cocktail of drugs that could take him wherever in his mind palace he needed to go.

In the course of his experiments, he had tried numerous substances in his quest for the perfect combination of neuronal stimulation. Ketamine and ritalin quickly entered his Victorian box of treasures. Other drugs to target the specific neurotransmitters involved in memory seemed promising - cisapride,said to target type 4 serotonin receptors, had proved to have too many additional effects, and had made his memory retrieval worse, not better; lorcaserin, a weight loss drug, should have targeted the areas of the prefrontal cortex and hippocampus involved in memory but the results were disappointing. He even tried memantine, a drug then it's its early clinical trials for Alzheimer's. Even Ritalin, much loved by generations of students for its ability to improve both memory and attention, carried the risk of impairing the process of storing, filing and accessing memories if the incorrect dose was taken, or if it was mixed with other substances.

And there was the frustration for Sherlock as a chemist. However much research he did, it brought him down to the same simple facts; nobody really understood how memory worked. They knew which areas of the brain lit up when memories were stored and retrieved, they knew which neurotransmitters were activated in those areas, and yet the precise mechanisms remained unclear. Too much neurotransmitter release would impair access to the memories in his subconscious as surely as insufficient amounts. Balance was the key, and that was impossible to predict by any means other than experimentation. And so the number of black notebooks on the back of his work bench expanded in number as slowly, gradually he expanded his repertoire.

And if at times he felt the need for a purer form of escape, then wasn't that part of the work, too? Didn't it enable him to continue to do what he did? Solve crimes, bring the guilty to justice, restore order to an otherwise chaotic world?

Sherlock's fingers reached for another vial of white powder. This one didn't sparkle in the light, but it made his heart beat a little faster by its very proximity. Later, he promised himself. When all of this is over and done with. Later.

There was no time for self-indulgence now. What he needed was something to get him through this pain in his chest that was intensifying as the lingering effects of the ketamine wore off. Something to enable him to do what was needed - to show John the truth in a way that he couldn't doubt. To show him what Mary was, and at the same time ensure that she remained to him what she had always been - his best and most enduring protection. His own personal bodyguard, his very own assassin. Trained to kill, willing and able to protect John. He couldn't have planned it better himself. He carefully replaced the vial back in the box and allowed himself a moment to imagine 'what if'. What if he hadn't left? What if he'd taken John with him? What if he hadn't allowed himself to get lost in the thrill of the chase and stayed away so long?

Could it every have stayed the same? He and John in 221B, doing what they did best - fighting the good fight, solving crimes, exploring the underside of London together. Would it have changed anyway? Would John eventually have met a girlfriend who stuck, who not even Sherlock's constant barrage of derogatory commentary could push John away from? Would he have met Mary even if Sherlock had still been around, and would Sherlock have failed to realise what she was until it was too late? Or would he have had the courage to know when he was beaten and let John go, handed him over as it were to the best woman for the job. He closed his eyes and swallowed, allowing himself a rare moment of self-pity. The wisdom of hind-sight was a strange thing, but sentiment would not solve this, and it would not keep John safe, only he could do that.

He stood up, stretched out muscles cramped from sitting in one position for so long, and then reached for a vial, then another and then a third, closed the box lid with a snap and placed it carefully to one side before reaching for the micro-scale which stood ready at the side of the bench, ready to weigh out the ingredients of a new cocktail. This one had only one requirement. It had to keep Sherlock alert, and on his feet for the next two hours. Enough time for Billy to lure John to Leinster Gardens, another hidden space in London, and for him to set up the trap that would force Mary to reveal to her husband what she really was. Two hours to destroy his only friend, and then to build his hopes back up again. Wasn't that how it was done? And after that his work would be complete. Even Magnussen no longer had the pull that he had previously. Sherlock wasn't sure that he wanted to save the world anymore. He just wanted to save John Watson.

When he was sure that he had the right combination of ingredients, he reached again for his box and lifted up the secret compartment in the base, revealing a tourniquet and a depressingly modern set of insulin syringes. He had toyed with the idea of antique victorian silver syringes, but common sense and the fear of injecting bacteria as part of his cocktail had won in the end.

He lit the bunsen burner on the work bench, carefully dissolved the white powder with a small amount of sterile water in a test-tube and just enough base to turn it into a solution when held over the top of the blue flame of the Bunsen burner with tongs. Then and only then did Sherlock take off his coat, roll up his sleeve and prepare to do what he must. 'For John,' he told himself. Promising himself as always that this would be the very last time. That after this he would let the room remain hidden, forgotten. That he wouldn't need to return here again. And yet knowing at the same time that it was never the last time, that there would always be another case, another reason to return.

Five minutes later he was striding down the street towards Leinster Gardens, the pain of his wounds forgotten. And if his eyes were a little glassy, and a pupils a little more constricted than would have been expected given the darkness of the evening then who was going to notice? A second vial in his pocket contained a different cocktail, designed to be rubbed along the gum and absorbed from there it would be easy to get it into his system without John realising what he was doing. Just enough to get him through the evening, to do what he must. For John.

* * *

This runs parallel in time with chapter 19 of Fratros, Eros and Agape, and immediately before chapter 20, but is also designed to be read in isolation.

Huge thanks to sevenpercentfor her impeccable advice and betaing as always, and also to ThessalyMc and GhyllWyne for the inspiration and advice.

More Fratros coming soon...


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